Application of mass spectrometry in polyoxometalate chemistry

With the fast development of polyoxometalate (POM) chemistry, there is a need to bridge the gap between solid-state structure and solution properties of POM which is helpful to design and synthesize function-directed POMs. Conventional analytical techniques have significant drawbacks especially for study of special structured POMs and investigation of the formation mechanism in solutions. With the development of soft ionization techniques--matrix assisted laser desorption ionization (MALDI) and especially electrospray ionization (ESI), mass spectrometry (MS) became one of most powerful analytical techniques applicable to simple inorganic, coordination and organometallic compounds. Polyoxometalates are a kind of inorganic polymers which are ideal candidates to be examined using high-resolution mass spectrometry since they are intrinsically charged and have characteristic isotopic envelopes, resulting from the stable isotopes of W and Mo, which can be precisely fitted to determine the exact formula. This paper reviews the research progress of the application of mass spectrometry in polyoxometalate chemistry. ESI-MS can provide vital information of the cluster composition in solution and be used to probe the self-assembly mechanism in solution. In addition, the potential applications of mass spectrometry in the field are stated.